How to do a chin-up?

Okay as a fairly unfit female, I'm finding it nigh impossible to perform chin-ups! I'm at a normal weight, but I hardly have the upper body strength.

I've been practising by starting at the 'top' and slowly lowering myself. Raising myself, I can only get my elbows to a 90 degree angle and no higher. I also do a few sets of weights each day for a short period.

Does anyone have any tips on how to practice?

Here is a great web page with lots of info:

http://www.stumptuous.com/mistressing-the-pul lup

I'm working on this too, and its tough, but I've given myself a year to get to my goal of 5 unassisted pull-ups!

Put a bench or stool under your pull-up bar to support you at the bottom of the pull-up...This is where you are trying to support your entire weight, and the hardest part  The bench should be just tall enough so that your feet/toes will touch it when you're at the bottom of the move.  YOu can then use your legs to give you a boost up to the top.  Try this with chin-ups also.  Doing this has really improved my pull-up/chin-up.

Alternatively, I've seen people use big rubber bands to support their weight, but your gym may not have these.

Bragging alert!!

I'm proud to say that today I did:

1 set of 4 chin-ups

1 set of 3 chin-ups

1 pull-up (palms facing away!!)

I noticed all the guys stop to watch.  :)

Thanks sunflower59 and scantin for the great advice! I'll give it all a go!

And nice work jenningermany, being able to do chin-ups is certainly worth bragging about!